The known device has a comparatively small metal housing for a radiation source which can emit infrared or ultraviolet radiation. The housing is secured by means of pivots between the free ends of a resilient supporting member. The pivot has a cylindrical part secured to the supporting member, which part is pressed against a recess co-operating therewith in the housing so that the housing is resistably rotatable with respect to the member. The user can easily adjust the housing in a desired position.
However, it has been found that such pivots are unsuitable for use in large and relatively heavy devices such as sun canopies whose housing is secured between fairly robust suspension members since then due to its weight, the housing tends to move from its set position; the housing cannot be put in a given position to a sufficient reproducible extent.